Trends in the ecological strategies and evolution of millipedes (Diplopoda)

Five main morphotypes (polyxenoid, glomeroid, juloid, polydesmoid, and platydesmoid) are denoted and five ecomorphotypes, i.e. life‐forms (stratobionts, troglobionts, geobionts, subcorticolous xylobionts, and epiphytobionts) are oudined in the Class Diplopoda. Their distribution and that of separate higher taxa show a number of marked ecological and geographical trends. The Diplopoda as a whole is believed to be originally a forest floor‐dwelling group, with stratobionts dominating everywhere, this life‐form having given rise to all other derivative, apparently synchronously evolved life‐forms. The poor development of the derived life‐forms points to their recent evolution, probably brought about by die great climatic changes of the last 2–3 Ma. The European fauna is characteristically dominated by the life‐form of stratobionts and in most areas by the juloid morphotype. However, the distribution of orders is strongly skewed. The habitats in Europe with richest millipede faunas seem to be temperate forests in the Atlantic zone and central mountain chains, where the Order Chordeumatida is strongly represented. This area contains several long‐term, or Ice Age, refugia. Further to the north, soudi and east, especially in open landscapes, along with an increasingly continental/Mediterranean climate, representatives of the juloid morphotype, mainly members of the Order Julida, become proportionately more common, while general species diversity falls. The ecological strategies of millipedes are rooted both in the group's phylogeny and in die Earth's history. In Europe diis history is peculiar owing to the east‐west lie of the principal mountain chains, and repeated glaciations have led to the development of a mixed, fully migratory, recent European faunal kernel, or nucleus, which is forced south and cornered in die largely mountainous western and central parts of the Continent during glaciations. Many local endemics have evolved in these areas, including a substantial proportion of cavernicolous species.